This research proposal will utilize the cellular differentiation system leading to spore formation in bacillus subtilis in an investigation of the genetic and biochemical control of membrane synthesis. Membranes isolated from mutants blocked in different stages of differentiation will be characterized. In addition, the alterations of DNA-dependent RNA polymerase associated with the nuclear fraction of the sporulating cells will be characterized. The restriction of sporulating phenotypes for certain bacteriophages will also be studied in relation to the biochemical changes associated with differentiation. These studies are aimed at elucidating the nature of the genetic control of biochemical functions during cellular differentiation.